1-(N-Trifluoroacetylamino)alkylphosphonic acids: synthesis and properties

Summary. The 1-(N-trifluoroacetylamino)alkylphosphonic acids (TFA-AA^P) – sub-products in the synthesis of O,O-dialkyl 1-(N-trifluoroacetylamino)alkylphosphonates and O,O-diethyl 1-aminoalkylphosphonates, were synthesized in two-stage transformations of 1-aminoalkylphosphonic acids including: trifluoroacetylation of 1-aminoalkylphosphonic acids (AA^P) using a trifluoroacetic anhydride/trifluoroacetic acid reagent (AA^P + TFAA/TFA→2) and subsequent hydrolysis of the intermediary compounds 2 into desired TFA-AA^P (2→TFA-AA^P). These intermediates 2 presented mixtures of the type of mixed anhydrides of TFAA and 1-(N-trifluoroacetylamino)alkylphosphonic, pyrophosphonic and polyphosphonic acids, which underwent rapid and quantitative conversion to corresponding TFA-AA^P during treatment with an excess of water. The title acids were isolated by direct evaporation of the corresponding post-reaction mixtures, and their physicochemical proprieties, including deacylation abilities, were determined. TFA-AA^P compounds can be re-converted into the starting amino acids AA^P under respectively mild conditions (AA^P→TFA-AA^P→AA^P).